Various medical testing procedures require penetrating the patient's skin with a medical device such as a short needle-like lance, often to a depth less than the subcutaneous tissue layer. The lance typically carries a testing agent that may result in the reaction to the skin cells surrounding the penetrated region defined as the testing area.
The testing area is typically observed once the patient is exposed to the agent by the medical device for any reaction to the skin cells. If a reaction to the agent occurs, traumatized skin cells on the patient at the testing area become inflamed and are often no larger than two or three centimeters. For some patients, it is possible for the skin reaction to take fifteen to twenty minutes.
Conventional allergy testing often referred to as a prick test similarly uses a single lance carrying an allergen that penetrates a testing area in order to release the allergen into the patient's skin. The testing area is then monitored for a period of time to see if any traumatized skin cells are generated, thus providing a visible allergic reaction.